[Tinderboxsky (Steve)]

After I purchased the Mini Tower Pro early last year to upgrade to a go to system for visual observing, I started thinking about how I could adapt the quick release dovetail system that I had been using for quick set up and take down on my external fixed pier. I have developed a prototype fixed pier adaptor for the Mini Tower Pro out of spare ply and other leftovers in the workshop. It has been working so well that it might be some time before I make the final one out of aluminium.

So, a series of photos to explain:

Existing observing pier with a Vixen dovetail rail that was used previously to quickly attach a Vixen Port Mount. The marks are accurate SCP markers for alignment purposes.

Top side of simple prototype base plate adaptor for the Mini Tower Pro made out of two pieces of quality waterproof 13 mm ply, glued together. Three stainless bolts have had grooves cut in their 6 side faces and then epoxied into the ply. Three simple level adjusting bolts were made from a length of spare threaded stainless steel rod and nylon rod.

Underside of the base plate adaptor with a leftover vixen dovetail clamp screwed to the ply. The bolt shown is used to attach the base plate adaptor to the mount.

First stage of assembly: The base plate adaptor is fixed firmly to the pier with the dovetail clamp and the three adjusting bolts are levelled accurately.

Second stage of assembly: Firmly bolt the base plate adaptor to the mount taking care not to turn the levelling bolts.

Third stage of assembly: Simply attach the mount to the pier using the dovetail clamp. Then complete the standard alignment routine. The mount is now fully set up and aligned.

At the end of the observing session return the mount to the Park Position and remove the scope and accessories. It is then a simple matter to release the dovetail clamp to remove the mount. If the base plate adaptor is left firmly attached to the mount then, when the mount is put back on the pier for the next observing session, it will be in exactly the same position and orientation. The go to controller will recall the setting from the previous session’s Park Position and be immediately ready for slewing to your first target.

To simplify carrying and storing the mount I have fixed another small section of dovetail to a flat piece of wood set in a plastic crate as per the photos.

So, the setup routine now is simply; attach the mount to the pier using the dovetail clamp, attach the accessories and telescope, turn on and slew to first the first observing target.

It is working very well, with no loss of accuracy. I was concerned that the ply might flex, or that the epoxied nuts might move in the wood, resulting in some loss of pointing accuracy, but this has not been the case. The fact that I have the scope and mount accurately balanced in in all planes probably helps with minimising any flexure.
The only change I will make when I eventually machine the final version out of some scrap aluminium is to either make or buy a much broader dovetail and clamp. I am thinking of something the size of a Losmandy D clamp and dovetail. Not sure when this will happen as the prototype is working well and there are other things gobbling up my time.

Anyhow hope this might be of interest and trigger some ideas of your own.

Cheers

Steve.

PS, as you can see, I have replaced the standard counter weight with a cradle to hold the battery that powers the mount. This has simplified things further, in particular, the balancing of the scope and mount accurately in all planes. I’ll explain this in another thread if people are interested.